Fix issue in contact/friction between btMultibody and btRigidBody (external force/torque of btRigidBody was not taken into account during contact/friction setup)
Allow 0.1 mm slop in contact, to avoid loosing contact. Todo: allow contacts with positive distance in multibody solver.
add wsg50 gripper with modified r2d2 gripper tip
expose a fudge factor to scale inertia, to make grasping more stable
(until we have better grasping contact model/implementation)
Fix uninitialized variable jointDamping/jointFriction in SDF importer
Add SDF <pose> parsing in visual, inertial, collision elements.
Slight improvement in TinyRender loading performance of largish meshes (30k vertices)
Reduce #define MAX_SDF_BODIES to 500, due to some issue in client code, todo: figure out what the issue is.
b3RobotSimAPI support SDF file loading
Tiny improvement in OpenGL hardware renderer lighting, to distinguish faces without textures
